Botulinum toxin 'dramatically' improves OAB symptoms

May 15, 2006

Paris-Botulinum toxin A (Botox) proves to be a safe,effective treatment modality in combating overactive bladdersymptoms in patients with idiopathic detrusor overactivity, Britishresearchers reported at the European Association of Urology annualcongress here.

"The administration of botulinum toxin A injections at 200 units appears to be safe and greatly improves OAB symptoms as well as urodynamic parameters compared to placebo in patients with refractory idiopathic detrusor overactivity for at least up to 24 weeks," said Arun Sahai, BSc, a urology fellow at Guy's Hospital and GKT School of Medicine, London, working with Mohammad Shamim Khan, MD, and Prokar Dasgupta, MD.

Botulinum toxin A is currently used in some patients suffering from neurogenic detrusor overactivity, although it is not FDA-approved for this indication. The toxin has also recently has been tried in patients with idiopathic detrusor overactivity (IDO) in open-label studies and has shown good results, effectively lasting anywhere from 6 to 12 months. According to Dr. Sahai, physicians are slowly turning their sights to this exciting treatment modality in patients with IDO, dramatically improving patients' quality of life, particularly in those who show no real benefit with or who cannot tolerate standard anticholinergic medications.

Twenty injections at 10 units/mL per injection site were administered. The investigator assessed voiding diary, urodynamic, and quality of life parameters at baseline and at 4 weeks and 12 weeks post injection. At 12 weeks, the patients were unblinded, and further open-label follow-up occurred in the botulinum toxin group at 24 weeks.

Assessment of quality of life using three validated questionnaires (King's Health Questionnaire, Incontinence Impact Questionnaire short form, and the Urogenital Distress Inventory short form) also showed dramatic benefits of botulinum toxin A compared to placebo. Data from the extension study suggested that the benefits seen in urodynamic, voiding diary, and quality of life parameters in the botulinum toxin group were maintained at 24 weeks compared with baseline values.

Careful counseling required

Dr. Sahai conceded that despite the overwhelmingly positive response of botulinum toxin A injections on the bladder, careful patient counseling is necessary during the consent process, and patients should be made aware of the possibility of poor bladder emptying following treatment. Six patients in the study, all of whom had botulinum toxin A treatment, required post-treatment clean intermittent self-catheterization. Urinary tract infection occurred in 17.6% of the patients.

When questioned why the rate of urinary tract infections was so high, Dr. Sahai responded that the everyday rate of urinary tract infections when using botulinum toxin lies between 10% and 20%, according to the published literature.

"In our study, five out of those seven patients who had a urinary tract infection were performing clean intermittent self-catheterization, which can increase the risk of acquiring an infection," he said.

The study was sponsored by a grant from the Bristish Urological Foundation and an unrestricted educational grant from Allergan, Ltd., which provided botulinum toxin free of charge for study patients.